I am so sorry to hear about your Dad. Now, I would love to hear my Dad's voice on a tape somewhere - do keep it if you can.
You have done right by him an respected his wishes and he will know that you made things good as he had wanted. Making all the calls is a lonely job and repeating everything so many times is a horrible thing to have to do so I hope that is now done and you won't have to keep doing it any more.
Courage and peace to you, your mum, your dh and your son.